[davi]

Hi folks,

I recently compared the isolated music track on The Matrix DVD to the official CD release of The Matrix score. To my surprise, the pitch of the music on the DVD is a SEMITONE HIGHER than on the CD. Track for track.

The only other CD-DVD pair I own is Jaws, so I tried the same thing. And again, the DVD was a semitone higher (sharper) than the CD.

I'm using Australian Region 4 DVDs in my iMac DV (Matshita SR-8184 DVD-ROM drive, firmware revision AA31). I tried the CDs in both the iMac and my Bose sound system: same result. Unfortunately I don't have a second DVD player to compare to the iMac's.

I've had the iMac for a year but haven't noticed this before because the pitch-shift is imperceptible until you play the DVD and CD side by side. And then it's glaringly obvious.

The only explantion I've come up with so far is this: the DVD is recorded at 24 frames per second. The Australian PAL TV format is 25fps. That extra frame every second translates into a 4.1% speed and frequency increase.

My first question is: WHY???!

Shouldn�t region 4 DVDs - manufactured in Australia for Australian hardware - take this into account? Is the player/disc manufacturer's solution to squeezing DVD's 24 frames into PAL's 25 to speed up playback?

So if a DVD movie is recorded at 24fps, how do I make it play at 24fps?

Please help!

DAVI

[King Chung Huang]

The reason it's a semitone higher is because the movie is playing back at 25 fps, rather than 24fps. This is the preferred method of transferring film to PAL video. In NTSC, a 3:2 pulldown method is used.

[davi]

Thanks for that response, King.

But if DVD manufacturers in Australia are routinely speeding up DVDs to make them fit PAL specifications, then it's a conspiracy to defraud consumers, who think that they're seeing and hearing the same thing on DVD as they saw and heard in the cinema.

If the powers-that-be think it's acceptable to change the speed and pitch of a movie that a director, editor and composer have slaved over for months, then we're in big trouble.

Is there any solution to this? Is there any way for me to see and hear what the film-makers intended? Or are we Australians stuck with sped-up DVDs?

Please help!

[davi]

I found a good confirmation of this at http://www.howstuffworks.com/video-format2.htm

"On a PAL or SECAM system ... the television presents a complete picture 25 times a second. This is pretty close to 24 frames per second, so if you make a direct conversion showing one complete film frame in every full video frame, the movie plays pretty well, just a tiny bit FASTER. The main thing you might notice is that all the sound has a slightly HIGHER pitch."

I did a test by playing region 1 (USA) and region 4 (Australia) versions of the same DVD movie side by side. Sure enough, the PAL region 4 DVD was a bit higher/faster than the NTSC region 1 DVD. It's obvious that the Australian one was sped up to 25fps and the USA one was correctly encoded at 24fps.

The part I can't believe is that PAL DVD manufacturers have been getting away with this! It's like Australians and Europeans are being duped into watching faster and higher movies! Is there anyone out there who agrees that this is outrageous?

It seems that the solution is to use region 1 DVDs! Unfortunately they're way too expensive to mail-order to Australia at the moment.

Any thoughts?

[King Chung Huang]

Well, the studios aren't attempting to "dupe" viewers in PAL regions with this method. The reality is that this is the best solution for transferring 24 fps film to 25 fps PAL. The next closest alternative would be to repeat a frame every 24 frames, which would result in a noticeable (and very annoying) stutter. This is just a reality of 50Hz power, and 25fps video.

[davi]

So what's happening when I watch region 1 DVDs, encoded at 24fps, on multi-region Australian equipment, such as my iMac? The picture looks the same as the PAL version, but the speed and sound are "correct". Where does the adjustment to 25fps take place in that process? Is the iMac doing something to the 24fps data before it reaches my monitor?

[King Chung Huang]

Region 1 DVDs, which are targeted at an NTSC using audience, use a telecine 3:2 pulldown methd to transfer from film to video. In this process, a repeating pattern of 3 fields/2 fields is used to convert fro 24fps video to 30fps TV (actually, 29.97 fps).

Here's a quick Photoshop image I whipped up to explain.



Basically, the first frame is repeated in two field, frame two in three fields, frame three in two field, frame four in three fields, and so on. So this results in half of the frames in the film being shown in 2 fields, and the other half of the frames being shown in 3 fields. This equals (12 * 2) + (12 * 3) = 60 fields per second! Of course, since NTSC is not 30 fps, but 29.97 fps, a little more tweaking has to occur for it to line up properly.

This is why Region 1 DVDs play at the same speed as the film. However, this transfer method results in an extremely slight stutter since each frame lasts for a different amount of time. Almost nobody sees it, but if you look really closely at high speed pans, you'll see it. Also, this method breaks up the progressively imaged frames from film and breaks it up into fields, which IMHO is quite ugly. You can see it if you were to rip a raw video track from a DVD and watch it in its native form. The Apple DVD Player automatically compensates for this so that you can see a nice progressive frame on your Mac.

Edit: Just wanted to note that Region 1 DVDs aren't encoded at 24fps, they're encoded at 29.97 fps since they target an NTSC audience.

[This message has been edited by King Chung Huang (edited 03-01-2001).]